A Pelleted Combination of Raw Soyhulls and Condensed Corn Steep Liquor for Lactating Dairy Cows

An experiment was conducted to evaluate the effect of a pelleted combination of raw soyhulls and condensed corn steep liquor on performance and plasma metabolites when fed to replace a portion of the grain and forage in diets for lactating dairy cows. The raw soybean hull-corn steep liquor pellet (SHSL) contained 24.2% crude protein, 8.7% rumen undegradable protein, 28.9% acid detergent fiber, 36.7% neutral detergent fiber, and 2.5% ether extract (% of dry matter, [DM]). Eighteen multiparous Holstein cows were assigned to one of three diets in a replicated 3 x 3 Latin square design with 28-d periods. Cows were blocked by pretreatment body weight and energy-corrected milk (ECM) and assigned to control, SHSL (20.7% of diet DM), or pelleted raw soybean hulls ([PSH] 14.3% of diet DM). The SHSL product replaced 6.2% alfalfa hay, 3.7% corn silage, 6.6% corn, and 3.3% soybean meal (SBM), and 1.7% expeller SBM replaced solvent SBM in order to maintain dietary levels of rumen undegradable protein. PSH replaced 6.2% alfalfa hay, 3.7% corn silage, and 5.1% corn. Diet crude protein (%) and energy density (Mcal/kg NEL) were 16.6 and 1.64, 16.3 and 1.65, 17.1 and 1.63 for control, SHSL, and PSH, respectively. Cows fed PSH consumed more DM than cows fed control, with the intake of cows fed SHSL being intermediate. SHSL and PSH increased ECM, milk protein, and solids-notfat and showed higher concentrations of milk and plasma urea N and total alpha-amino N in plasma than the control diet. Furthermore, feeding SHSL tended to improve the ratio of ECM to DM intake. There was no effect of diet on concentrations of total essential and nonessential amino acids in plasma. These production data suggest SHSL can replace a portion of the forage, grain, and SBM in diets for lactating dairy cows without decreasing lactational performance.